To cope with increasing mobile traffic demands and higher expectations for better user experience, macro network nodes are complemented with low power network nodes, e.g. indoor low power network nodes or indoor systems like Radio Dot System, RDS, and Distributed Antenna system, DAS, since the majority of mobile traffic is generated in indoor locations. The term macro network node generally refers to a “conventional” network node in contrast to low power network nodes, which generally have a significant lower transmission power than the macro network node. However, it shall be pointed out that the low power network node may also be placed outdoor. Enterprise services are moreover being proposed by operators, offering companies and its employees a solution with a range of services and wireless access in their premises. Compared to traditional mobile broadband services, it is expected that enterprise services would target much higher capacity (data demand per user) and user experience targets. For example, enterprise users should get unlimited data when in the office. This is typically not the case for mobile broadband services where user data volumes are limited per month.
Wireless communications use both licensed and unlicensed spectrum. 3rd Generation Partnership Project, 3GPP, technologies typically use licensed spectrum where a single operator uses a part of the licensed spectrum in a country or other area. Unlicensed spectrum is available for e.g. Wi-Fi, and it may be used by several parties and operators in the same area. Sharing rules and techniques are employed in order to avoid uncoordinated interference between the users.
When deploying indoor solutions in an enterprise building, it may be difficult and costly to achieve indoor dominance, i.e. that the indoor system (of low power network nodes) provides stronger signal for wireless devices inside the building than the outdoor network node (generally a macro network node) that is relatively close to the building thereby having a coverage area encompassing at least parts of the building, see FIG. 1. In FIG. 1, a wireless device 110 is illustrated being located relatively close to a wall 105 of the building 100, wherein the low power base station 120 may not be able to establish dominance over the macro network node 130. In the event that many indoor users (wireless devices) are connected to the macro/outdoor network node 130, a capacity imbalance may occur due to the enterprise user demands possible being much higher than the demands for users (wireless devices) 135 outside the building not being offered the unlimited data in enterprise areas.
Indoor dominance is required to connect indoor users to the indoor system when a small cell selection offset is used. A small cell is generally referred to, in this disclosure, as a coverage area of a low power network node. In e.g. Long Term Evolution, LTE, a cell selection offset of up to 9 dB is possible but in many cases the difference between signals of the macro/outdoor network node and low power network node signals may be much larger. The reason is that the macro/outdoor network node generally uses much higher power (e.g. 60-80 W) than the low power network node (<1 W). There can also be line-of-sight propagation from the macro/outdoor network node towards the building or a low building penetration loss that increase this effect. The low power network nodes also use limited power to avoid radiation effects since users (wireless devices) may be very close to the antenna of a low power network node. The lack of indoor dominance may cause the indoor users to be connected to the macro/outdoor network node in these areas. As a result, there will be a negative impact on the macro/outdoor network node's capacity since the enterprise users are expected to demand a high amount of data due to the unlimited data service offerings (normally part of enterprise offerings). This will negatively affect all users connected to the macro network node, i.e. regular mobile broadband service users not connected to the indoor system.
The 3GPP LTE Release-10 specifications have been standardised, supporting Component Carrier, CC, bandwidths up to 20 MHz (which is the maximal 3GPP LTE Release-8 carrier bandwidth). An LTE Rel-10 operation wider than 20 MHz is possible and appear as a number of LTE CCs to an LTE Rel-10 terminal. The straightforward way to obtain bandwidths wider than 20 MHz is by means of Carrier Aggregation, CA. CA implies that a 3GPP LTE Release-10 terminal may receive multiple CC, where the CC have, or at least the possibility to have, the same structure as a 3GPP LTE Release-8 carrier.
CCs are also referred to as cells or serving cells. More specifically, in an LTE network the cells aggregated by a terminal, i.e. wireless device, are denoted primary serving cell, PCell, and secondary serving cells, SCells. The term serving cell comprises both PCell and SCells. All wireless devices have one PCell which is considered “more important”, i.e. vital control signalling and other important signalling is typically handled via the PCell. Uplink control signalling is currently always sent on a wireless device's PCell. The component carrier configured as the PCell is the primary CC (i.e. the Primary Component Carrier, PCC) whereas all other component carriers are secondary serving cells. The wireless device may send and receive data both on the PCell and SCells. For control signalling such as scheduling commands this could either be configured to only be transmitted and received on the PCell but where the commands are also valid for SCell, or it can be configured to be transmitted and received on both PCell and SCells. Regardless of the mode of operation, the wireless device may only need to read the broadcast channel in order to acquire system information parameters on the Primary Component Carrier, PCC. System information related to the Secondary Component Carriers, SCC, (i.e. a CC on which the UE has SCells) may be provided to the wireless device in dedicated Radio Resource Control, RRC, messages.
The licensed spectrum is limited and must be used for providing at least primary serving cell to wireless devices. This combined with dominance issues between low power network node(s) and neighbouring network node poses problems for efficiently making use of available resources, licensed and unlicensed. In this disclosure, a neighbouring network node is generally a macro/outdoor network node having higher transmission power than the low power network node.